Q: Dr. Eppley, I am interested in getting a forehead augmentation. I know that there are different materials to use, one of which is PMMA. I have a few questions about PMMA. Does PMMA bone cement have a risk of granulomas like PMMA injections? Are the outlines of it visible? Does it have a risk of extrusion? Thank you!
A: In answer to your questions:
1) PMMA cranioplasty material does not cause granulomatous reactions. That is a unique phenomenon of small PMMA particles in soft tissue
2) Besides getting getting the right contour and amount of augmentation, one of the major objectives of any form of cranioplasty is to get a smooth transition form the material to the surrounding bone. This usually requires intraoperative burring of the edges after the material is set to have feather edges so there are not visible outlines after surgery.
3) There is no risk of extrusion of a PMMA cranioplasty. Extrusion of any implant material occurs because it is either placing excessive pressure on the overlying soft tissues or is infected and it is being pushed out by the pressure of the purulent fluid build-up. A PMMA cranioplasty is rigidly fixed to the underlying bone by microscrews prior to it being placed as a rebar method. This prevents any micromotion or displacement after surgery. The material is also impregnated with antibiotics which provides several weeks of antibiotic release after surgery for infection prevention.
Dr. Barry Eppley
Q: I have had forehead reshaping surgery about a year ago with PMMA resulting in a very unsatisfactory result. None of the areas I was concerned with have been addressed and there is significant visible irregularities as a result of the surgeons incompetence at the task. I wanted to know how long I should wait before seeking revision surgery? I would ideally like to have it nine months after the first surgery. Also how would the existing material (PMMA) affect how the surgery will be performed? Is there a greater risk of infection or is the surgery going to be significantly more difficult??
A: Sorry to hear of your unsatisfactory outcome from your cranioplasty procedure. From a technical standpoint, you could have revisional surgery at any time. There is no advantage or disadvantage to doing it now or years down the road. The material is set and stable and can be smoothed and rehaped, or added to, at any time. There is no increased risk of infection or increased difficulty in performing the procedure at any point. Revisional cranioplasty, when PMMA is the indwelling material, is actually slightly easier to do as the scalp tissues lift off of the material very easily as they do not bind or adhere to the PMMA. PMMA becomes encapsulated rather than integrated to the overlying soft tissues and the underlying bone. My observation is that patients having secondary scalp flaps raised report little to no pain afterwards although the swelling and the bruising will likely be similar.
Dr. Barry Eppley